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12#include <linux/bcd.h>
13#include <linux/kernel.h>
14#include <linux/gfp.h>
15#include <linux/delay.h>
16#include <linux/jiffies.h>
17#include <linux/rtc.h>
18#include <linux/of.h>
19#include <linux/of_device.h>
20#include <linux/platform_device.h>
21#include <linux/io.h>
22#include <linux/module.h>
23
24#define RTC_SIZE 8
25
26#define RTC_CONTROL 0
27#define RTC_CENTURY 0
28#define RTC_SECONDS 1
29#define RTC_MINUTES 2
30#define RTC_HOURS 3
31#define RTC_DAY 4
32#define RTC_DATE 5
33#define RTC_MONTH 6
34#define RTC_YEAR 7
35
36#define RTC_CENTURY_MASK 0x3f
37#define RTC_SECONDS_MASK 0x7f
38#define RTC_DAY_MASK 0x07
39
40
41#define RTC_WRITE 0x80
42#define RTC_READ 0x40
43
44
45#define RTC_STOP 0x80
46
47
48#define RTC_BATT_FLAG 0x80
49
50struct rtc_plat_data {
51 void __iomem *ioaddr_nvram;
52 void __iomem *ioaddr_rtc;
53 unsigned long last_jiffies;
54};
55
56static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
57{
58 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
59 void __iomem *ioaddr = pdata->ioaddr_rtc;
60 u8 century;
61
62 century = bin2bcd((tm->tm_year + 1900) / 100);
63
64 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
65
66 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
67 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
68 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
69 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
70 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
71 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
72 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
73
74
75 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
76 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
77 return 0;
78}
79
80static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
81{
82 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
83 void __iomem *ioaddr = pdata->ioaddr_rtc;
84 unsigned int year, month, day, hour, minute, second, week;
85 unsigned int century;
86
87
88 if (pdata->last_jiffies == jiffies)
89 msleep(1);
90 pdata->last_jiffies = jiffies;
91 writeb(RTC_READ, ioaddr + RTC_CONTROL);
92 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
93 minute = readb(ioaddr + RTC_MINUTES);
94 hour = readb(ioaddr + RTC_HOURS);
95 day = readb(ioaddr + RTC_DATE);
96 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
97 month = readb(ioaddr + RTC_MONTH);
98 year = readb(ioaddr + RTC_YEAR);
99 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
100 writeb(0, ioaddr + RTC_CONTROL);
101 tm->tm_sec = bcd2bin(second);
102 tm->tm_min = bcd2bin(minute);
103 tm->tm_hour = bcd2bin(hour);
104 tm->tm_mday = bcd2bin(day);
105 tm->tm_wday = bcd2bin(week);
106 tm->tm_mon = bcd2bin(month) - 1;
107
108 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
109
110 return 0;
111}
112
113static const struct rtc_class_ops ds1742_rtc_ops = {
114 .read_time = ds1742_rtc_read_time,
115 .set_time = ds1742_rtc_set_time,
116};
117
118static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,
119 size_t bytes)
120{
121 struct rtc_plat_data *pdata = priv;
122 void __iomem *ioaddr = pdata->ioaddr_nvram;
123 u8 *buf = val;
124
125 for (; bytes; bytes--)
126 *buf++ = readb(ioaddr + pos++);
127 return 0;
128}
129
130static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,
131 size_t bytes)
132{
133 struct rtc_plat_data *pdata = priv;
134 void __iomem *ioaddr = pdata->ioaddr_nvram;
135 u8 *buf = val;
136
137 for (; bytes; bytes--)
138 writeb(*buf++, ioaddr + pos++);
139 return 0;
140}
141
142static int ds1742_rtc_probe(struct platform_device *pdev)
143{
144 struct rtc_device *rtc;
145 struct resource *res;
146 unsigned int cen, sec;
147 struct rtc_plat_data *pdata;
148 void __iomem *ioaddr;
149 int ret = 0;
150 struct nvmem_config nvmem_cfg = {
151 .name = "ds1742_nvram",
152 .reg_read = ds1742_nvram_read,
153 .reg_write = ds1742_nvram_write,
154 };
155
156
157 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
158 if (!pdata)
159 return -ENOMEM;
160
161 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
162 ioaddr = devm_ioremap_resource(&pdev->dev, res);
163 if (IS_ERR(ioaddr))
164 return PTR_ERR(ioaddr);
165
166 pdata->ioaddr_nvram = ioaddr;
167 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;
168
169 nvmem_cfg.size = resource_size(res) - RTC_SIZE;
170 nvmem_cfg.priv = pdata;
171
172
173 ioaddr = pdata->ioaddr_rtc;
174 sec = readb(ioaddr + RTC_SECONDS);
175 if (sec & RTC_STOP) {
176 sec &= RTC_SECONDS_MASK;
177 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
178 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
179 writeb(sec, ioaddr + RTC_SECONDS);
180 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
181 }
182 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
183 dev_warn(&pdev->dev, "voltage-low detected.\n");
184
185 pdata->last_jiffies = jiffies;
186 platform_set_drvdata(pdev, pdata);
187
188 rtc = devm_rtc_allocate_device(&pdev->dev);
189 if (IS_ERR(rtc))
190 return PTR_ERR(rtc);
191
192 rtc->ops = &ds1742_rtc_ops;
193
194 ret = devm_rtc_register_device(rtc);
195 if (ret)
196 return ret;
197
198 devm_rtc_nvmem_register(rtc, &nvmem_cfg);
199
200 return 0;
201}
202
203static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
204 { .compatible = "maxim,ds1742", },
205 { }
206};
207MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
208
209static struct platform_driver ds1742_rtc_driver = {
210 .probe = ds1742_rtc_probe,
211 .driver = {
212 .name = "rtc-ds1742",
213 .of_match_table = of_match_ptr(ds1742_rtc_of_match),
214 },
215};
216
217module_platform_driver(ds1742_rtc_driver);
218
219MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
220MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
221MODULE_LICENSE("GPL");
222MODULE_ALIAS("platform:rtc-ds1742");
223
